Rather than evaluating a structural analog to generate preclinical data in tumor-bearing dogs in support of a human clinical candidate, another recent study evaluated PCI-32765 (ibrutinib, ImbruvicaTM), a first-in-class inhibitor of the Bruton tyrosine kinase (Btk), in dogs with spontaneous B-cell lymphoma prior to first-in-in-human studies (64). This evidence concerns the gene BTK and B-cell non-Hodgkin lymphoma.